Title: Climatic gradients and Douglas-fir growth: Water limits growth from stand to region
1Climatic gradients and Douglas-fir growth Water
limits growth from stand to region
Jeremy Littell JISAO CSES Climate Impacts Group
UW College of Forest Resources David L.
Peterson, USFS PWFSL Michael Tjoelker, UW College
of Forest Resources
2Douglas-fir and climate
- Bio-climatic range of Douglas-fir fairly well
understood - But presence/absence ? life history - growth is
also important - Climatic limitations on growth should vary
substantially across range
Thompson et al.
3High elevation / northern mountain hemlock
Photo J. Littell
Low elevation / southern mountain hemlock
Photo C. Webber
Interior ponderosa pine
Photo C. Woodhouse
4Why an emphasis on tree growth?
- Compared to biogeography, we know relatively
little about long-term, broad-scale climatic
controls on life-history processes of trees - Especially true in non-plantation, mountain
ecosystem settings where topography, soils, etc.
interact with climate - Establishment, growth, and mortality are the
mechanisms of species range changes and are tied
to climate these are the ecological mechanisms
behind productivity, carbon sequestration, and
ecohydrology
5Scales of Climatic Influence
- Global - hemispheric climate change
- Hemispheric to regional climatic variability
- Regional to local physiographic
- Local topographic
- Goal exploit network of tree ring chronologies
to understand local vs. large scale controls on
growth
6CLIMET (Climate-Landscape Interactions on a
Mountain Ecosystem Transect)
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10Climate Dimensions of the Sample Transect
11First Detrending Negative exponential, negative
linear, or zero slope fit
Mean standardized chronology
Second Detrending Cubic smoothing spline
(preserves 50 variance at 128yr frequency, 99
at 41 yr)
12ONP
Within each park, the variability in tree-growth
is similar across low, middle, and high
elevations. Main differences between west and
east (note 2000s drought)
NCNP
IPNF
GNP
13Correlating Tree-growth and Climate
- Two scales of monthly climate data
- Climatological divisional climate (1895-2002)
- Year-of-growth and year-prior PPT, Avg. T, PDSI
calculated water balance deficit - Biological (1/8 x 1/8 ) VIC climate
(1915-2002) - Year-of-growth and year-prior PPT, T (Avg., Max.,
Min.), Soil Moisture, ET, SWE - Seasonal climate variables
- Climate division ANN, H2OANN, NDJFM, AMJ, MJJAS,
JJA, JA for all PPT, T, PDSI - VIC Selected combinations of months for
different variables - Water balance deficit
- Gridded Bouwman 30cm field capacity data set 50
and 100mm - Assumed non-linear declining availability
function - Estimated PET - AET deficit
- Milne et al. surplus water PPT- ET / PPT
14General patterns of growth-climate correlations
are similar for divisional and VIC PPT and T
climate.
- PPT
- (M) JJ Year-of
- JA (S) Year-prior
- Avg. T
- JJ Year of, JA prior
- Apr and Nov prior
- Important differences
- VIC precipitation and divisional temperature
are better correlates in most chronologies. - Seasonality relationships different VIC
captures a longer season of sensitivity to
precipitation.
ONP relationship stronger
15Prior JS results similar to divisional average T
JJ results weak in other analyses
Nov. results similar to VIC and divisional
average T
- VIC allows separation of the influence of minimum
and maximum temperature - VIC Min/Max T
- JJ year of (esp. GNP and ONP), - JA year prior
for maximum temperature (esp. IPNF and NCNP) (hot
summers) - ON year prior for minimum temperature (warmer
autumns)
16Deficit (Div.) -JJ year of growth -JAS year
prior PDSI (Div.) May.-Sep ASO year
prior Soil Moisture (VIC) Entire year
prior Evapotransp. (VIC) Mixed (AET context
varies with PET)
17- Seasonal Aggregation
- Divisional Climate
- Prior JA temperature
- Prior JA precipitation
- VIC Climate
- Prior JA precipitation
- Prior JJAS max. temp.
- current AMJJ precip.
- current AMJJ max. temp.
- Prior ANN. soil moisture
18The magnitude of the correlation between seasonal
hydrological variables and tree-growth depends on
the position of the plot along a gradient of
surplus water in the environment.
19The portion of the tree-growth signal that is
common to all plots is closely related to
independent reconstructions of PDSI. However,
there are differences across the transect in
fidelity to that signal.
20Summary Growth-Climate Relationships
- Most frequent patterns of correlations point to
combined influence of (-) temperature and ()
precipitation during summer - Underscored by PDSI () and water balance deficit
(-), esp. in IPNF and GNP. - Some cool season () temp. and (-) snow
relationships, primarily in ONP and NCNP.
Bonsai PSME, Saint Mary, Glacier National Park
21Spencer Wood
Mike Case, Mike Tjoelker, Sarah Gobbs, Sean
Hill
Melissa Hornbein
2003-2004 Field Crews
Alex Karpoff
Greg Pederson
Sam Cushman
Carson Sprenger